Voltage Source Converter Active Damping Control
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Solution Overview
Problem
Voltage source converters connected to the same DC system and interconnected on the AC side experience oscillations when operating in frequency and voltage control mode, which can lead to instability and power imbalances during grid restoration or wind farm power transmission.
Innovation Solution
Implementing an active damping control module within the control unit of each converter, using a waveform control module to generate AC waveforms and create a virtual impedance by processing phase currents in the dq frame to dampen oscillations, thereby avoiding the need for physical components like resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both converters operate in frequency and voltage control mode with interconnected AC sides, then automatic power sharing between poles is improved, but oscillations between the two converters occur
Solution Approach 1:
The control unit measures the phase current and calculates an oscillation damping control signal based on the measured value, creating a feedback mechanism that actively counteracts oscillations between converters while maintaining frequency and voltage control mode operation
Solution Approach 2:
The invention introduces a virtual impedance parameter through control signaling that dynamically adjusts the system's electrical characteristics to damp oscillations without changing the physical converter operating mode or hardware configuration
2Stability of the object's composition
If physical components like resistors are used to damp oscillations, then oscillation damping is achieved, but cost and device footprint increase
Solution Approach 1:
The invention replaces physical electrical components (resistors) with a control-based virtual impedance mechanism, substituting hardware-based oscillation damping with software-based control signaling that achieves the same stabilizing effect without additional physical devices
Solution Approach 2:
The control unit creates a virtual copy of impedance behavior through control algorithms that mimic the damping effect of physical resistors, allowing oscillation suppression without introducing actual physical damping components
Data Source
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AI summary
The invention is concerned with a first voltage source converter (14) and converter station (10) comprising such a first voltage source converter (14) as well as to a method and computer program product for controlling the first voltage source converter. The first voltage source converter (14) has a DC side for connection to a DC system (22), has an AC side for connection to an AC system (ACB1) and is interconnected with an AC side of a second voltage source converter (16), which has a DC side connected to the DC system(24). The first voltage source converter (14) comprises a number of converter valve pairs, each being connected to a corresponding AC phase of the AC system (ACB1) and a control unit controlling the converter valves to generate at least one AC waveform and to reduce oscillations between the converters (14, 16).